Logger.h

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// Copyright Onix Solutions Limited [OnixS]. All rights reserved.
//
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// protected by copyright law and international copyright treaties.
//
// Access to and use of the software is governed by the terms of the applicable
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// agreements granting a non-assignable, non-transferable and non-exclusive license
// to use the software for it's own data processing purposes under the terms defined
// in the Agreement.
//
// Except as otherwise granted within the terms of the Agreement, copying or
// reproduction of any part of this source code or associated reference material
// to any other location for further reproduction or redistribution, and any
// amendments to this copyright notice, are expressly prohibited.
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//

#pragma once

#include <OnixS/CME/MDH/Integral.h>
#include <OnixS/CME/MDH/String.h>

ONIXS_CMEMDH_NAMESPACE_BEGIN

/// Defines severity levels for log entries.
struct ONIXS_CMEMDH_LTWT LogSeverity
{
    /// Enumeration base.
    typedef UInt32 Base;

    /// Log alternates.
    enum Enum
    {
        /// Only important information like
        /// warnings and errors will be logged.
        ///
        /// Mode is not suitable for further log
        /// replays, because no market data is stored.
        Important = 10,

        /// Handler will log miscellaneous aspects
        /// related with its execution like changes
        /// in state, network data obtained, etc. All
        /// critical important information like warnings
        /// and errors will be logged as well.
        ///
        /// Most suitable mode to produce logs for further replay.
        Regular = 50,

        /// In addition to the data logged in 'Regular'
        /// mode, Handler will output additional information
        /// like step-by-step changes into books, step-by-step
        /// processing of received network packets.
        Debug = 100
    };
};

/// Serializes log severity constant.
ONIXS_CMEMDH_EXPORTED
void toStr(std::string&, LogSeverity::Enum);

/// Serializes log severity constant.
inline std::string toStr(LogSeverity::Enum mode)
{
    std::string str;

    toStr(str, mode);

    return str;
}

/// Deserializes log severity constant.
ONIXS_CMEMDH_EXPORTED
bool fromStr(LogSeverity::Enum&, const Char*, size_t);

/// Categories for information being logged.
struct ONIXS_CMEMDH_LTWT LogCategory
{
    // Enumeration base.
    typedef UInt32 Base;

    /// Categories for information being logged.
    enum Enum
    {
        /// Log entry represents an error.
        Error,

        /// Log entry represents a warning.
        Warning,

        /// Log entry represents informational message.
        Info,

        /// Log entry represents debug information.
        Debug
    };
};

/// Serializes log category constant.
ONIXS_CMEMDH_EXPORTED
void toStr(std::string&, LogCategory::Enum);

/// Serializes log category constant.
inline std::string toStr(LogCategory::Enum mode)
{
    std::string str;

    toStr(str, mode);

    return str;
}

/// Deserializes log category constant.
ONIXS_CMEMDH_EXPORTED
bool fromStr(LogCategory::Enum&, const Char*, size_t);

/// Abstraction of log entry in logging services.
class ONIXS_CMEMDH_EXPORTED LogEntry
{
public:
    /// Specifies category of information being logged.
    virtual void category(LogCategory::Enum) = 0;

    /// Specifies source of information being logged.
    virtual void source(const StrRef&) = 0;

    /// Editable text to be a message of log entry.
    virtual std::string& message() = 0;

    /// Commits entry into a log and releases the instance.
    ///
    /// Once given member is invoked, further invocation
    /// of other members is not allowed as instance may be
    /// disposed and thus do not exist anymore.
    virtual void commit() = 0;

protected:
    /// Life-time is managed by Logger.
    LogEntry() {}

    /// Life-time is managed by Logger.
    virtual ~LogEntry() {}

private:
    // Object copying is not supposed.

    LogEntry(const LogEntry&);
    LogEntry& operator=(const LogEntry&);
};

/// Abstraction of logger.
class ONIXS_CMEMDH_EXPORTED Logger
{
public:
    /// Finalizes the instance.
    virtual ~Logger() {}

    /// Basic information on the implementation
    /// of the logging services.
    virtual void info(std::string&) = 0;

    /// Adds entry to the log.
    ///
    /// Actual content can be added through the
    /// interface of LogEntry and LogEvent classes.
    ///
    /// @return Instance of LogEntry to build message
    /// being added into the log or NULL if severity
    /// of entry being added does not correspond to
    /// logger's configuration.
    virtual LogEntry* addEntry(LogSeverity::Enum) = 0;

protected:
    /// Only descendants are to be created.
    Logger() {}

private:
    // Object copying is not supposed.

    Logger(const Logger&);
    Logger& operator=(const Logger&);
};

ONIXS_CMEMDH_NAMESPACE_END